Squashfs is a
highly compressed read−only filesystem for Linux. It
uses zlib compression to compress both files, inodes and
directories. Inodes in the system are very small and all
blocks are packed to minimize data overhead. Block sizes
greater than 4K are supported up to a maximum of 64K.

Squashfs is
intended for general read−only filesystem use, for
archival use (i.e. in cases where a .tar.gz file may be
used), and in constrained block device/memory systems (e.g.
embedded systems) where low overhead is needed.

Compress using
filter1,filter2,...,filterN in turn (in addition to no
filter), and choose the best compression. Available filters:
x86, arm, armthumb, powerpc, sparc, ia64.

−Xdict−size
DICT_SIZE

Use DICT_SIZE as the XZ
dictionary size. The dictionary size can be specified as a
percentage of the block size, or as an absolute value. The
dictionary size must be less than or equal to the block size
and 8192 bytes or larger. It must also be storable in the xz
header as either 2^n or as 2^n+2^(n+1). Example
dict−sizes are 75%, 50%, 37.5%, 25%, or 32K, 16K, 8K
etc.